Almost all spiders are venomous. The families Uloboridae (tiny things a few mm across at most) wrap prey in webbing instead and pour digestive juices on it, dissolving the prey alive instead. There is a single species that has evolved to become vegetarian, a species of jumping spider, that lives on the type of acacias that have evolved symbiotic relationships with colonies of vicious ants that kill invading critters by biting and stinging and that in return the acacias provide both structures such as hollow swollen bases at the bottom of their thorns for the colonies to live in, and specialized little orangey-yellow, rounded high protein food packages born at the tips of their leaflets. These, this particular, unique kind of spider, feeds upon, making it so far as is known, the only vegetarian spider in the world. The much larger Mesothelae are also nonvenomous, although the Mesothelids do have quite large, mechanically powerful fangs, oriented in the downward-stabbing Mygalomorph configuration (compare to E.g funnelwebs (Atrax, Hadronyche (tree funnelwebs), mouse spiders and the purse webs, the last of which have european members and quite powerful fangs although the venom is not known to be dangerous to people, they live their lives within constructs of webbing in the shape of tubes, and stab upward with large, long fangs to impale their prey. The others are, surprise surprise, ozzy critters and unlike the purse-webs, these are highly venomous and to primates, lethal. The Mesothelae are unusual in that they are thought, IIRC, to have originated during the evolutionary splitting from a segmented common ancestor when the spiders and scorpions diverged to form their respective groups within the arachnids and retain plates of segmentation on the top of their abdomens. Trapdoor spiders essentially, or living in burrows and relying on speed, surprise and brute force to overpower prey, since they lack venom, or if they do not, then they lack the ducted fangs needed to deliver it. Similar in that respect to Solifugae, the Solifugids, or camel spiders are not true spiders but a subgroup of their own right within the arachnids, most nonvenomous although at least one, indian species does possess both venom and some means to deliver it. Large, hairy and known for being extremely quick, they too use their huge jaws to rip prey to pieces.
There is one, perhaps another two small suborders of true spiders containing tiny animals similar to the Uloboridae that like them, lack venom completely also.